sarah briggs wrote:Does any one know why the Enzymes from the respiring yeast cells cause Meth Blue to become colourelss (the actual scienific reasoning), My teacher hinted that ions where involved??Thanks

Heh, no; all my teacher told me was that it turns colourless when there's enzyme activity- beyond that, i really haven't a clue. I don't think it really matters, anyway.

To be honest i used a colorimeter once and am pretty sure i broke it. unfortunetly it seems that we're meant to use it, but i haven't got a clue how you use it atall? Do we have to describe in full how we use it? or just that state that we did use it?and if we do have to describe in full could someone please tell me how. thank you x

my advice would be don't bother the solution is to opaque for it to work well - count the cells under a microscope. Sorry if your set on using one i am sure someone will work out how - i jsut dislike them.

Physics more and more knowledge about less and less. - Still it's the basis for all else.

i'm using a colorimeter as it is pretty easy to use
make a blank with no meth blue put in cuvette press R. then one by one add the heated experimented on samples and press T. you get the % transmission of light. This can then be drawn on a graph really easily. The only bad thing is that they don't measure exactly below one. If the number 1 is flashing it means below one.

a colorimeter has to be used to make the plan of alevel standard otherwise it would be like GCSE cwk...
and the seperate solutiond have to be heated up to a constant temp befor they can be mixed together so that it makes a fair test, otherwise all substantces wont be of the same temp.
and in theory part u have to say how u need a pH buffer of 7-7.4 to maintain the pH and keep it constant.
And how subtrate-complexes are less likely in a temp above optimum and eventually stop. cos 3-d active site looses its 3-d ness